Electric discharge tube with deflection control



Nov. 9 1948. A. J. M. VAN QVERBEEK 2,453,647

ELECTRIC DISCHARGE TUBEWITH DEFLE CTION CONTROL filed May 2, 1946 f If[I ATMRA/[x Patented Nov. 9 1948 UNITED STATES O F CE I a -2,45a6 fsLaoraicmsoHA G TUBE W g anemones contact Ad ianne, Johannes I w Marieran beek, ,Eirrd hoyen, Netherlands, assignpr,

d trustee i,

s gjmnents, toHartford National Bank u liii ipany, Hartfotd," C n -J aApplication has @1946, seem No. 2666,655 sInrtheNethei lands August 15,194% inte t;

This invention relatesto an electric discharge tube in which an electronbeams "controlled by deflection and in such 'a tube.

It is known in electric'dis'charge tubes comprising at least two anodesto group the electrons in beams and to transmit these beams by means ofdeflecting plates :to one of thetwo anodes in accordance with thevoltage between the :de'flecting plates. Various kinds of such tubes areknown, it being possible for a tube to be con structed iin such mannerthat the electrons traverse substantially straight paths from which theyonly deviate by reason of :the contro l vol tage of the deflecting,platesandaccording to a further construction o'fthe discharge tube theelectrons are so influenced by particular shapes and bias voltagesof-the deflecting plate lfOf them will traverse curved paths'wi'thoutdepending on the control voltage of the deflecting plates. Theseelectron paths are more or less curved by means of the control voltageof the deflecting plates so that, in consequence, the electrons willimpinge on one or the other anode in accordance with the said controlvoltage.

Especially the latter construction is of very great advantage for tubeswith double control in which the density of the electron beam iscontrolled by a control electrode which is nearer to the cathode thanthe deflecting control electrode since in such discharge tubes electronswhich have arrived in the second control space are prevented by the tubeconstruction itself from returning to the first control space so thatthese two spaces are well separated and the tube is thus adapted toperform two separate operations. One limitation of such tubes withdeflection control is, however, that the gain and consequently thesensitivity is comparatively small.

Now, this difiiculty may be obviated by the use of an electron dischargetube according to the invention in which the electrons traversing curvedpaths are controlled by deflection by means of two or more deflectingmembers that have a curved surface whose hollow side is nearer to theflow of electrons. By means of this subdivision of the deflecting memberinto a plurality of parts of given shape it is possible to control thepotential along the surface of the said member in such manner thatgreater sensitivity compared with the known constructions is obtained.Preferably, such voltages are applied that throughout the member aregularly varying potential is set up whose gradient varies along thesurface of the deflecting members. The influence addition to a'e'ircuitincludin agram 5;Gla/ims. (Cl. 250%1593 of the potential variations of"portions of the deflecting member aiccord-ing to the invention on theelectron "paths will be set outmore 'ful'ly hereinafter-by referencetothe accompanying drawing and by a comarisen with the influence of is yaried relatively 'tothe cathode or to the point from which the electronbeam proceeds its insilence on the rays of electrons is similar to thatof a displacement of the member parallel to itself. The influence of a'variation of the potenttal gradient along the deflecting member on thepaths of electrons may be compared with that of a rotation of thismember. It may be seenJirom the drawing that the control in the secondmanner results in a far greater deviation of the beam of electrons thanin the first manner. Referring to Fig. 1 the curve I represents theelectron path associated with a position of the deflecting member 131which is designated by a full line. If the potential of the deflectingmember rises its action corresponds to a displacement of the deflectingmember to the positicn D11 shown in dotted lines and for this purposethe electrons will traverse a path according to the dotted curve II. Thedeviation from the electron'path at the point A is consequently througha distance a. Fig. 2 shows different electron paths III, IV and V forthe case of the potential gradient along the deflecting member D beingvaried. If the position DIII of the deflecting member corresponds to thecase of the potential along this member being constant, the lines DIVand UV will show the positions that correspond to potential difierencesalong the deflecting member, position DIV corresponding to the case ofthe left hand part of the member having a negative potential relativelyto the right hand part, whereas this is reversed for position By. Thevariation of the electron paths for the various positions of thedeflecting member are designated by the curves III, IV and V, It isobvious that the deflections b and c at the point A are substantiallylarger than the distance a of Fig. 1.

In a construction according to the invention the varying potential alongthe deflecting member is carried into practice in a simple manner. Thesimplest manner may be dividing the deflecting member of cylindricalshape by severing it along a straight line into two parts between whicha control voltage is placed, Fig. 3 diagrammatically shows anarrangement in which this means is made use of. The electrons enteringfrom the cathode K into the deflecting space are sent by variation ofthe varying potential that prevails along the deflecting member by meansof the control voltage Vd either towards the anode A1 or towards theanode A2. It is obvious that this manner of deflection control may beused irrespective of the manner in which the electrons enter into thedeflection control space.

The described simple manner of obtaining a variable potential gradientalong the deflecting member may have the disadvantage that a sufficientgradual transition is not obtained. A much more uniform potentialdistribution is obtained, for example, if the severing line of the twoparts has a shape curved or broken in a definite manner. It isadvantageous, for example, to shape this line in zigzag fashion as shownin Fig. 4. This figure is a plan of a deflecting member which is dividedinto two parts I and 2 along a zigzagshaped line of demarcation. It isalso possible to divide the deflecting member into more parts, it beingalso possible for the severinglines to have different shapes. In thiscase the parts may have fixed voltages relatively to eachother, forexample by means of a potentiometer circuit as shown in Fig. 5. Thecontrolling deflection voltage Va is placed across a potentiometer P towhich parts of the deflecting member are connected at various points.The electrons proceeding from the cathode K are thus controlled so as tobe able to reach either the anode A1 or the anode A2.

What I claim is:

1. An electric discharge tube comprising a cathode for generating anelectron stream, a pair of anodes, a deflecting member for deflectingthe electron stream to one or the other of the anodes according to thepotential on said deflecting memher, said member comprising a pluralityof spaced parts which jointly form'a curved surface whose concave sidefaces the path of the deflected e1ectron stream, and in which adescribing line of the enveloping surface of the member forms a rightangle with the direction of deflection.

, 2. An electric discharge tube as claimed in claim 1, wherein the lineof demarcation of the various parts of the deflecting member has a curveor broken shape.

3. An electric discharge tube as claimed in claim 1, wherein the line ofdemarcation between two various parts of the deflecting member iszigzag-shaped.

REFERENCES CITED The following references are of record in the file ofthis patent:

' UNITED STATES PATENTS Number Name Date 2,161,466 Henneberg June 6,1939 2,332,876 Uhlmann Oct. 26, 1943 FOREIGN PATENTS Number Country Date115,986 Australia Oct. 22, 1942 851,534 France Jan. 10, 1940

